Being ex RAF the ex-military get my vote as I know the standards required of them. My experiance of many civil instructors is that they are just sat there waiting for an airline job and let you know it. Ex mill guys have been there and have a wealth of experiance to pass on in a consistant manner.
This is not to say that there are not some suberb civilian FI's out there as well. High hours dedicated instructors who teach for the love of the job not the hope of an airline job.
I have met more than a few d*&*^head "jet jocks" in the mess as well, but this is the same in all walks of life!
Bose-X
(looking forward to his foramtion course with Ultimate High shortly!)